Method of forming powder metal phosphor matrix and gripper structures in wall support

ABSTRACT

A method of fabricating a support structure. In one embodiment, the method is comprised of providing a mold. The mold is for defining the physical dimension of the support structure. The mold is disposed upon a substrate surface. In one embodiment, the method is further comprised of depositing a powder into the mold. The present method is further comprised of compacting the powder deposited in the mold. The compacting forms the support structure. In one embodiment, the method is further comprised of removing the mold from the substrate surface upon which it is disposed. The removal of the mold exposes the support structure. The fabricated support structure is then implementable during assembly of a display device. In one embodiment, the powder deposited in the mold is a metal powder.

FIELD OF THE INVENTION

The present invention relates to display device fabrication. Moreparticularly, the present invention relates to the technology andfabrication of flat panel displays, e.g., field emission displays.

BACKGROUND OF THE INVENTION

Advancements in electronics and computer display technologies havecreated new categories of display devices as well as enablingimprovements upon existing display technologies. New categories ofdisplay devices include FPDs, (flat panel displays), e.g., TFTs (thinfilm technology), LCDs (liquid crystal display), AMLCDs (active matrixliquid crystal display), and the like. Improvements upon existingdisplay technologies such as CRTs (cathode ray tube) include greaterresolution, a more diminutive dot pitch, ever increasing display screensize, and the number of recognizable colors, which has increased frommonochrome (two) color to 24-bit (over 16 million) colors and higher.

However, of the display technologies mentioned above, including LCDs,not one is without certain drawbacks. For example, neither LCDs orAMLCDs can provide adequate viewing when viewed from an off-centerangle, and they require backlighting which requires yet more power. TFTsare subject to immense quality control difficulties associated with eachpixel's switching element, produced using integrated circuit techniques.Further, most FPDs cost substantially more than a CRT of an equivalentsize. In fact, none of the FPDs or CRTs have been able to meet all ofthe needs for improving power consumption, increasing brightnessefficiency, increased video response, improved viewing angles, cooleroperating temperatures, providing full color range, scaleability,ruggedness, and packaging.

In an attempt to provide a display device which responds to andovercomes the above list of needs, another class of display deviceswhich utilize flat panel display technology has been developed. This newclass of FPD (flat panel display) is called a FED (field emissiondisplay), also commonly called TCRT (thin cathode ray tube). The TCRTdisplay is, as the name implies, a thin cathode ray tube. Accordingly,the TCRT has, on the average, a thickness of +/−8 millimeters, whereasthe thickness of a conventional CRT is usually over 100 millimeters,dependent upon the size of the display.

The TCRT display has numerous other advantages over the conventionalCRT, including, but not limited to, greater power efficiency, reducedoperating temperature which equates to longer life for the display,reduced weight and foot print, faster response time to fast-movinggraphic images, e.g., streaming video, and many others.

Even with the above mentioned improvements, the TCRT is not withoutcertain shortcomings. For example, fabricating a TCRT requires that theback cathode side and front anode side (also called the faceplate)portions of the TCRT display be sealed together under a vacuum, whichforms the tube, through which the graphic images are presented. Duringthe application of the vacuum concurrent with the sealing process, thevacuum can result in forces as high as high fourteen and one-half poundsper square inch bearing down on the two portions being sealed. Toprevent the collapse of either of the sides, cathode or anode, supportstructures or walls disposed interposed between the two sides are neededto prevent such an occurrence. Because of the thinness of the TCRTdisplay being fabricated, the support structures must be strong enoughto support the cathode side and anode side during the vacuum and sealingprocess while being thin enough so as to not adversely deflect theelectron beams. Further, the support structures must be relatively easyto manufacture and cost effective, or risk having an overly expensivedisplay product price, effectively reducing possible market share.

In one example to attempt to provide a support-structure for the backcathode side and/or the front faceplate, materials having apredominantly polymer base, e.g., polyimides or polyamides wereimplemented. Unfortunately, polymers such as polyimides and polyamidesare prone to excessive gas emissions during tube operation, such thateven after outgassing, they are well known in the art to continue togenerate gas within the display tube upon electron bombardment duringdisplay operation. This continual generation of gas during displayoperation causes a reduction of display performance and also potentiallyreduces the operating life of the display device. Additionally, thepolymers, (polyimides and polyamides) are very expensive, both in rawmaterials and in the processing costs related to the construction of thewall supports. Further, these materials have a low reflective index,which reduces the overall performance of the display, and they exhibitpoor electrical conductivity.

Thus a need exists for a support structure that provides a reduction inemitted outgasses during display operation. Furthermore, it is desirableto provide a support structure that has increased reflective propertiesso as to provide greater luminous efficiency. It is also desirable toprovide a support structure that is less costly to manufacture. It isfurther desirable to provide a support structure that is electricallyconductive.

SUMMARY OF THE INVENTION

Accordingly, the present invention provides a support structure thatprovides a reduction in emitted outgasses during display operation. Thepresent invention further provides a support structure which achievesthe above listed accomplishment and which further provides increasedreflective properties so as to provide greater luminous efficiency. Thepresent invention additionally provides a support structure thatachieves the above listed accomplishments and which is less costly tomanufacture. The present invention further provides a support structurethat achieves the above listed accomplishments and which provides highelectrical conductivity.

The present invention provides a method for wall support fabrication. Inone embodiment, the method comprises providing a mold. The mold isutilized for defining the physical dimension of the support structure.In the present embodiment, the mold is disposed upon a substratesurface. The present method is further comprised of depositing a powderinto the mold. Further comprising the present method is compaction ofthe powder in the mold. In one embodiment, this compaction forms thesupport structure. The method of the present invention is furthercomprised of removing the mold from the substrate surface upon which itis disposed. The removal of the mold exposes the support structure. Thefabricated support structure is then implementable during assembly of adisplay device. In one embodiment, the powder used in filling the moldis a metal powder.

These and other objects and advantages of the present invention will nodoubt become obvious to those of ordinary skill in the art after havingread the following detailed description of the preferred embodimentswhich are illustrated in the various drawing figures.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and form a part ofthis specification, illustrate embodiments of the invention and,together with the description, serve to explain the principles of theinvention:

FIG. 1 is a cross-section of a display device upon which embodiments ofthe present invention may be practiced.

FIG. 2A is an illustration of a substrate upon which embodiments of thepresent invention may be disposed, in one embodiment of the presentinvention.

FIG. 2B is an illustration of the substrate of FIG. 2A with a molddisposed thereon for forming a support structure disposed thereon, inone embodiment of the present invention.

FIG. 2C is an illustration of the substrate of FIG. 2B depicting themold filled with a material used in the support structure, in oneembodiment of the present invention.

FIG. 2D is an illustration of the substrate of FIG. 2C depicting theremaining material, now formed as the support structure, subsequent tothe removal of the mold, in one embodiment of the present invention.

FIG. 2E is an illustration of a substrate upon which embodiments of thepresent invention can be practiced, in another embodiment of the presentinvention.

FIG. 2F is an illustration of the substrate of FIG. 2E with a molddisposed thereon for forming a support structure disposed thereon, inone embodiment of the present invention.

FIG. 2G is an illustration of the substrate and mold of FIG. 2F with themold filled with a material used in forming a support structure, in oneembodiment of the present invention.

FIG. 2H is an illustration of the substrate of FIG. 2E depicting theremaining material, now formed as the support structure, subsequent tothe removal of the mold, in one embodiment of the present invention.

FIG. 2J is an illustration of the substrate of FIG. 2E with a molddisposed thereon for forming a support structure disposed thereon, inanother embodiment of the present invention.

FIG. 2K is an illustration of the substrate and mold of FIG. 2J with themold filled with a material used in forming a support structure, in oneembodiment of the present invention.

FIG. 2L is an illustration of the substrate of FIG. 2G depicting theremaining material, now formed as a support structure, subsequent to theremoval of the mold, in one embodiment of the present invention.

FIG. 3A is an illustration of metal frame blank for molding wallpositions, into which a metal strip is stamped and formed, in oneembodiment of the present invention.

FIG. 3B is an illustration of the substrate of FIG. 2A upon which astamped and formed metal strip is disposed, in one embodiment of thepresent invention.

FIG. 3C is an illustration of a covering having been applied to themetal strip and substrate of FIG. 3B, in one embodiment of the presentinvention.

FIG. 3D is an illustration of the covering, which remains after themetal strip has been etched away, in one embodiment of the presentinvention.

FIG. 4A is an illustration of the substrate of FIG. 2A upon whichfurther embodiments of the present invention may be practiced.

FIG. 4B is an illustration of an additional layer disposed upon thesubstrate of FIG. 4A, prior to patterning, heat treating, and etchingbeing performed thereon, in one embodiment of the present invention.

FIG. 4C is an illustration of an additional layer, prior to beingdisposed upon the substrate of FIG. 4A, upon which patterning, heattreating, and etching has been performed, in one embodiment of thepresent invention.

FIG. 4D is an illustration of the resulting additional layer subsequentto patterning, heat treating, and etching performed thereon, in oneembodiment of the present invention.

FIG. 4E is an illustration of the substrate of FIG. 4A configured withtwo portions, each having different physical properties, in oneembodiment of the present invention.

FIG. 4F is an illustration of the two portioned substrate of FIG. 4E,subsequent to etching of the top portion; in one embodiment of thepresent invention.

FIG. 4G is an illustration of a substrate having a ceramic materialdisposed thereon, in one embodiment of the present invention.

FIG. 4H is an illustration of the substrate and ceramic material of FIG.4G having a photoresist layer disposed thereon.

FIG. 4J is an illustration of FIG. 4H subsequent to an etching processperformed thereon, in one embodiment of the present invention.

FIG. 5A is an illustration of the substrate of FIG. 2A upon whichfurther embodiments of the present invention may be practiced.

FIG. 5B is an illustration of an additional layer disposed upon thesubstrate of FIG. 5A, prior to patterning, heat treating, and etchingbeing performed thereon, in one embodiment of the present invention.

FIG. 5C is an illustration of an additional layer, prior to beingdisposed upon the substrate of FIG. 4A, upon which patterning, heattreating, and etching has been performed, in one embodiment of thepresent invention.

FIG. 5D is an illustration of the resulting additional layer subsequentto patterning, heat treating, and etching performed thereon, in oneembodiment of the present invention.

DETAILED DESCRIPTION

A method of fabricating a support structure utilizable in display deviceassembly is described. In the following description, for purposes ofexplanation, numerous specific details are set forth in order to providea thorough understanding of the present invention. It will be obvious,however, to one skilled in the art that the present invention may bepracticed without these specific details. In other instances, well-knownstructures and devices are shown in block diagram form in order to avoidobscuring the present invention.

Some portions of the detailed descriptions, which follow, are presentedin terms of procedures, steps, processes, and other symbolicrepresentations of operations concurrent with and implemented during theconstruction of a display device. These descriptions and representationsare the means used by those skilled in the display device fabricationand processing arts to most effectively convey the substance of theirwork to others skilled in the art. A procedure, executed step, logicblock, process, etc., is here, and generally, conceived to be aself-consistent sequence of steps or instructions leading to a desiredresult. The steps are those requiring physical manipulations of physicalquantities and which can be performed by humans and/or electronicallydriven machinery and apparatuses so designed and configured.

The present invention is discussed primarily in the context of a displaydevice, or more specifically, a flat panel display such as an FED (fieldemitting display) also commonly referred to as a TCRT (thin cathode raytube). However, it is appreciated that the present invention can be usedwith other types of display devices that have the capability to generateimages in an easily recognizable manner, including, but not limited toflat panel displays.

It should be appreciated that the methods and processes discussed in thefollowing can be applied to the cathode side of an FED as readily asupon the anode side (faceplate) of the display device. Additionally, themethods and processes can be applied to many different types of displaydevices, e.g., other FEDs, VFDs (vacuum fluorescent displays),electroluminescence displays, gas discharge plasma displays, and others.Accordingly, the following description of the processes and methodsutilized to fabricate support structures should not be construed aslimiting, but rather as exemplary so as properly depict embodiments ofthe present invention.

FIG. 1 is a cross-sectioned view of a display device 100, which, in oneembodiment, is a FED (field emission display) upon which embodiments ofthe present invention may be practiced. It is appreciated that thenormally present outer/protective casing of display device 100 is notshown so as to more easily describe and depict the components containedtherein. In one embodiment of the present invention, display device 100is a TCRT (thin cathode ray tube) display.

In the cross-sectioned view of display device 100 as depicted in FIG. 1,shown are the components which comprise an FED, which in one embodimentis a TCRT. Shown is glass back plate 102, the rear of the display deviceand is normally not viewed by a user, and onto which is disposed thecathode structure. The cathode structure consists of a combination ofrow metal 104, patterned resistor layer 106, dielectric 108, and columnmetal 110, emitter array 112, and a focusing structure 114. Also shownis faceplate 126 upon which is disposed black matrix 124, phosphor 122,and aluminum layer 120 Interposed between glass back plate 102 andfaceplate 126 is support structure 118, in one embodiment of the presentinvention. It is appreciated that embodiments of the present inventionare drawn to providing support structure 118.

FIG. 2A shows a component 200 of the display device 100 as shown in FIG.1. In one embodiment, component 200 is glass back plate 102, the cathodeside of display device 100 of FIG. 1. In one embodiment, component 200is faceplate 126 of display device 100 of FIG. 1. In this figure, FIG.2A, component 200 is faceplate 126 of FIG. 1, which provides thesubstrate 210 upon which embodiments of the present invention can bepracticed.

In one embodiment, substrate surface 210 of component 200, upon whichembodiments of the present invention are disposed, is the inside surfaceof the faceplate. When display device 100 is sealed, the inside surfaceis internally disposed within the display device, and the opposingoutward facing surface is that which is facing a user.

FIG. 2B shows substrate 210 having a photoresist mold 220, as indicatedby horizontal lines, disposed thereon, in one embodiment of the presentinvention. Photoresist mold 220 defines the physical dimensions of thesupport structure being fabricated. Photoresist mold 220 is a patternednegative image of that support structure being fabricated. In oneembodiment, photoresist mold 220 comprises trenches 215 having a widthranging from approximately ten to forty microns and a height rangingfrom approximately twenty to eighty microns. The dimensional tolerancesof trenches 215 is typically +/− five microns, in one embodiment of thepresent embodiment.

FIG. 2C shows a powder metal 230 having been deposited into photoresistmold 220 of substrate 210, in one embodiment of the present invention.In one embodiment, powder metal 230 is a getterable material, e.g.,zirconium or one that is titanium based. In one embodiment, a low CTE(coefficient of thermal expansion) filler is incorporated into powdermetal 230 to provide a CTE match with substrate 210 upon which it isdisposed. In this embodiment, powder metal 230 is a dry powder metal andis subject to dimensional variations until a compacting and sinteringprocess is performed thereon.

Still referring to FIG. 2C, subsequent to depositing powder metal 230into trenches 215 of mold 220, powder metal 230 is compacted. In oneembodiment, compaction of powder metal 230 is by conventional vibrationand (thermal) sintering. In another embodiment, microwave sintering iscombined with the convention vibration to compact powder metal. Inanother embodiment, ultrasonic processes are combined with thermalsintering, either conventional or microwave, to provide compaction. Itis appreciated that the temperature used to provide sintering does notreach the melting point of powder metal 230.

Referring to FIG. 2D, shown is powder metal 230 as the fabricated wallsupports, subsequent to a) the compaction and sintering process appliedthereto, as described in FIG. 2C, and b) the removal of photoresist mold220, in one embodiment of the present invention. In one embodiment,polishing of powder metal 230 may be performed prior to the removal ofphotoresist mold 220. In another embodiment, polishing of powder metal230 may be performed after removal of photoresist mold, 220. The removalof photoresist mold 220, can, in one embodiment, be accomplished bydissolution. In another embodiment, the removal of photoresist mold isby thermal burn-out.

FIG. 2E shows substrate 210, prior to disposition of a photoresist mold220 thereon, in another embodiment of the present invention. It isappreciated that substrate 210 of FIG. 2E is analogous to substrate 210of FIG. 2A.

FIG. 2F shows substrate 210 having a photoresist mold 220, as indicatedby horizontal lines, disposed thereon, in one embodiment of the presentinvention, and it is appreciated that substrate 210 and mold 220 of FIG.2F are analogous to substrate 210 and photoresist 220 of FIG. 2B.

FIG. 2G shows a powder metal paste 240 having been deposited intophotoresist mold 220 of substrate 210, in one embodiment of the presentinvention. In the present embodiment, powder metal paste 240 comprises apowder metal which is combined with a wax into a metal paste. In anotherembodiment, powder metal paste 240 comprises a powder metal which iscombined with a polymer-based binder into a metal paste. The physicalproperties of powder metal paste 240 are such that it has low viscosity,enabling gap-free (voidless) trench filling. Powder metal paste 240, inthis embodiment, is then pressed into trenches 215. In one example, asqueegee is utilized to press metal paste 240 into trenches 215. Inanother example, a doctor blade can be utilized to press metal paste 240into trenches 215. It should be appreciated that numerous otherimplements can be utilized to press metal paste 240 into trench 215,and, as such, those listed above should not be considered limiting, butrather as exemplary.

Still referring to FIG. 2G, and after the pressing of powder metal paste240 into trenches 215 of mold 220, powder metal paste 240 is dried, inone embodiment of the present invention. In one embodiment, the dryingof powder metal paste 240 is accomplished at temperatures ranging fromfifty to one hundred fifty degrees Celsius. This causes the binder tosolidify, thereby maintaining the desired shape and dimensions, even ifsubjected to an optional solvent dissolution of photoresist mold 220.Once dried, powder metal paste 240 is then heated to temperaturesranging from three hundred and fifty degrees to five hundred and fiftydegrees Celsius to accomplish sintering and binder burn-out, with anoptional concurrent photoresist mold 220 burn-out being accomplishedduring the same thermal cycle, in one embodiment.

It is appreciated that in one embodiment, the sintering of powder metalpaste 240 is performed as a separate step prior to the binder burn-out.This embodiment has the advantage of preventing shrinking or deformationof the support structures which can occur at elevated temperatures afterthe binder is removed. In one embodiment, a two stage thermal cycle isperformed. In the first step, the sintering is performed in a vacuum orinert atmosphere. The second step is performed in an air or oxygenatmosphere to encourage binder burn-out.

It is further appreciated that in one embodiment, complete densificationof powder metal paste 240 is not required during the sintering cycle,such that a structure having somewhat porous properties can provideadvantages regarding retentive properties, particularly when the grippermaterial is used for its vacuum gettering capabilities.

Referring now to FIG. 2H, shown are the remaining wall support (gripper)structures fabricated out of powder metal paste 240, subsequent tobinder burn-out, and in one embodiment, burn-out of photoresist mold220.

It is appreciated, in the present embodiment, that because the wallsupports are fabricated utilizing a powder metal, the fabricated metalwall supports provide reduced out-gassing and greater conductivity.Additionally, the metal wall supports provide a higher degree ofreflectivity than previously used materials. Further, in anotherembodiment, the metal wall supports can provide a more secure metal wallattachment scheme.

It is further appreciated that to ensure the success of the powder metalpaste technique described above, the design and composition of theparticles in the powder metal and the binder material utilized in powdermetal paste 240 are critical.

For example, in one embodiment, the use of particles that are less thattwenty microns, and preferable less than five microns in diameter aredesired to achieve accurate replication of the photoresist mold. In oneembodiment, a high loading or concentration of the particles, rangingfrom fifty to eighty percent, is used to retard tendencies of the powdermetal paste to shrink during the sintering process.

It is appreciated that the principles of eutectics can be utilized inthe reduction of required temperatures associated with processes in thefabrication of the support structures. In one embodiment, drawn toproviding CTE matching, the powder metal particles includes a mixture oftwo components. One component is the sintering agent, which accomplishesthe goal of effecting sintering at temperatures below five hundred andfifty degrees Celsius. The second component is the filling agent, whichaccomplishes the goal of enabling the powder metal paste to be adjustedso that the CTE (co-efficient of thermal expansion) of the powder metalpaste is compatible with the substrate upon which it is disposed, and toprevent shrinkage of the powder metal paste during sintering.

In one embodiment, drawn to providing a lowering of the sinteringtemperature, it is desirable to a) utilize metal particles which areeasily sintered in the temperature range of three hundred and fifty tofive hundred and fifty degrees Celsius. This is accomplished by theincorporation of low melting point alloying elements, e.g., Mg(magnesium), Cd (cadmium), Zn (zinc), Sn (tin), Cu (copper), Ag(silver), nearly any element used in brass or bronze alloys, bronzebrazing alloys or solders; b) utilize smaller particle sizes, e.g., inthe range of 0.1 to 5.0 microns; c) use of irregularly shaped and/ordistorted particles, such as those from a ball mill.

In addition, metal particles that are effective as gettering agents canbe beneficial when combined with the other elements. In one embodiment,these particles should contain elements, e.g., Ba (barium), Zr(zirconium), Mg (magnesium), Ti (titanium), Cs (cesium) and thoseelements classified as Lanthanides, such as Pr (praseodymium), Sm(samarium), and the like.

Further, in one embodiment, it is also desirable to utilize a binderthat encourages particle dispersion, resists flocculation (particleclumping), and reduces viscosity during the filling process.Additionally, the binder material should comprise physical propertieswhich prevents distortion and premature burn-out at temperatures up tothree hundred and fifty degrees Celsius, but is effectively andcompletely burned out at temperatures below five hundred and fiftydegrees Celsius. High temperature, cross-linked polyimides or polyamideor polyvinyl butylate or polyvinyl acrylate compounds are some of thematerials that are incorporatable in the powder metal paste.

Referring now to FIG. 2J, shown is substrate 210, analogous to substrate210, with a photoresist mold 220 disposed thereon, in one embodiment ofthe present invention. In the present embodiment, a particle jet isproduced so that mold 220 may be filled with metal 250 without nearlyany need for large amounts of binder compounds. In one embodiment, theparticles comprising metal 250 can be sprayed directly into the mold andcaused to sinter at modest temperatures before the mold itself isburned-out. This reduces the amount of volatile organics that areincorporated within metal 250 itself and potentially reduce shrinkageupon burnout of mold 220. In this embodiment, a spray gun it utilized todeposit metal 250 in mold 220, replacing the paste and doctor blade orsqueegee technique described in FIGS. 2F, 2G, and 2H, above. As theparticles are fluidized in a gas jet, they are better able to flow intoand fill the narrow and deep trenches 215 of mold 220 without needingadditional pressure from a doctor blade.

While a large number of powder spray techniques are available, most ofthese have been adopted for use in the paint industry where the powdersare generally polymer materials and easily fused together afterimpacting the working surface. The spray guns often use electrostaticcharging to enhance the acceleration of the particles, thereby reducingthe need to use high gas pressure in projecting the particles.

It is appreciated that the spray guns to be utilized in the depositionof metal 250, in this embodiment, are distinctly different from thosedescribed above in that the particles are not melted when impacting mold220. A colder method of particle application is used to remove thepossibility of melting or distorting photoresist mold 220 duringspray-on deposition of metal 250.

A distinction can also be made between powder spray, such as those usedin the paint industry, and kinetic spray which has been developed in thepowder metal industry. Kinetic spray is designed to project theparticles in a supersonic gas flow to increase the impact energy againsta substrate, e.g., substrate 210 of FIG. 2J. In this way the particlescan be consolidated without the need for prior melting. For the gripperapplication, however, complete densification of the powders is notnecessary, and may not be desirable if there is a risk of deformingphotoresist mold 220 in the process.

In one embodiment, a lower velocity powder spray can be implemented. Thelower velocity spray can include one or more of the followingcharacteristics. In one embodiment, consolidation of metal 250 isperformed in comparison to densification. A consolidated sprayed-on wallsupport structure 250 is sometimes referred to as a brown body, meaningthat it is a partially sintered material from which the binders havebeen previously burned-out. In this embodiment, the energy of the sprayneed only have enough velocity to bind the particles within mold 220 sothat the support structure 250 will not lose its shape and dimensionbefore a final sintering or strengthening process at highertemperatures. In one embodiment, ultrasonic compaction may also beutilized to promote binding without heating, thereby improving thestrength of the support structure 250 (brown body) while it is still inmold 220.

In one embodiment, the powders can be formulated using relatively lowmelting point materials, e.g., from the elements listed above indescribing FIGS. 2F, 2G, and 2H, so that relatively less kinetic energyis required to fuse them on impact with the surface. For example, copperand silver are but two of the low melting materials that will easilystick together upon impact.

It is appreciated that, in one embodiment, the particles can be madesmall, e.g., less than one micron, so as to reduce the energy necessaryfor effective fusion or interparticle binding. Additionally, a modestamount of organic volatilized binder can be incorporated in the spray toenhance cohesion of the brown body. In one embodiment, by volumepercent, this binder can comprise up to ten percent of the supportstructure 250 as opposed to thirty percent or more which is typical inpaste applications.

While the above embodiment describes a spray process which does notutilize additional heat being incorporated therein, in anotherembodiment a heated spray can assist in the consolidation process.

In one embodiment, a two component spray can be implemented to assistwith consolidation. The two component spray is comprised of one metalcomponent which is sprayed at a temperature close to its melting point,(the sintering agent) and the other metal component, of a higher meltingpoint, can be implemented as a filler compound.

In another embodiment, a multi-stage spray process may be implemented.In this embodiment, as a first part of the process, a first layer wouldbe spray deposited into mold 220 disposed on substrate 210, which wouldbe followed by a first polishing. Subsequent to completion of the firststep, a second layer is spray deposited, followed by a second polishingprocess.

In another embodiment, a polishing process can be performed on thedeposited material to precisely adjust the planarity and height of thedeposited material.

It is appreciated that in one embodiment of the present invention,because the support structure is fabricated out of metal and is black incolor, the steps associated with fabricating a black matrix, e.g., blackmatrix 124 of FIG. 1 and the steps associated with fabricating analuminum layer, e.g., aluminum layer 120 of FIG. 1 are eliminated. Inanother embodiment, the black matrix and aluminum layer are fabricatedin conjunction with the fabrication of the support structures interposedbetween the faceplate and the cathode.

Referring now to FIG. 3A, shown is metal frame blank 360 into whichmetal is placed, stamped, and formed, in one embodiment of the presentinvention. Once stamped and formed, metal strip 370, shown in FIG. 3B,is then disposed upon a substrate 310 shown in FIG. 3B (analogous tosubstrate 210 of FIG. 2A). The metal is deposited in troughs 365 whichdefine the physical dimensions of the metal strip being fabricated. Inthis embodiment, the metal strip is used to provide a negative image ofthe wall support structure being fabricated.

Referring to FIG. 3B, shown is the stamped and formed metal strip 370(as indicated by diagonal lines) disposed upon substrate 310, in oneembodiment of the present invention.

Referring to FIG. 3C, subsequent to the disposition of metal strip 370on substrate 310, a glaze 320 is applied to both substrate 310 and metalstrip 370, in one embodiment of the present invention. Subsequent to theapplication of glaze 320, in one embodiment, increased temperature isapplied to the assembly (metal strip 370 and substrate 310) so as toreflow the glaze, such that metal frame 370 is encapsulated by theglaze.

Referring to FIG. 3D, subsequent to the reflowing of glaze 320, metalstrip 370 is removed, such that glaze 320 remains, forming the wallsupport structure being fabricated. In one embodiment, the removal ofmetal strip 370 is by etching. The etching process simultaneouslyprovides retentive indentations (vertical grooves) in glaze 320, whichprovides for more secure wall confinement. In one embodiment, glaze 320,as the wall support structure, can then be patterned and etched to formthe black matrix for phosphor. In another embodiment, glaze 320 can beformulated to function as contrast filter, and as such would not besubjected to patterning and etching. Subsequently, conventionalprocesses are utilized to form black matrix and phosphor.

It is appreciated, in one embodiment, that because the wall supportstructure are fabricated out of a ceramic glaze, a reduction ofout-gassing from electrodesorbtion is realized. Further, the reductionin out-gassing provides for greater display performance and increasesthe life of the display.

In one embodiment of the present invention, it is appreciated that thefabrication of a black matrix, e.g., black matrix 124 of FIG. 1, and thefabrication of an aluminum layer, e.g., aluminum layer 122 of FIG. 1, isperformed in conjunction with the fabrication of the support structuresas described in FIGS. 3A to 3D.

In another method to fabricate support structures, glass, in acontinuous or sheet form, is utilized in the fabrication process. FIG.4A is an illustration of substrate 410 upon which embodiments of thepresent invention may be practiced. Substrate 410 is analogous tosubstrate 210 of FIG. 2A. In one embodiment, substrate 410 is D263glass. In another embodiment, substrate 410 is an alternative glass.

FIG. 4B is an illustration of substrate 410 of FIG. 4A with anadditional layer of glass, glass 420, bonded thereto. In one embodiment,diffusion bonding is utilized to bond glass 420 to substrate 410. Inanother embodiment, thin film sealing glass is utilized to bond glass420 to substrate 410. In one embodiment, glass 420 a photochemicallysensitive glass, e.g., Fotoform or ceram, and which has a thickness ofseventy-five micrometers. It is appreciated that glass 420 is bonded tosubstrate 410 prior to patterning, heat treating, and etching beingperformed upon glass 420. In one embodiment, CrO₃ is deposited upon thebonding side of glass 420 prior to deposition and bonding upon substrate410. CrO₃ is for the blackening of the bonding side of glass 420.

FIG. 4C is an illustration of additional layer of glass, glass 420patterned, heat treated, and etched prior to bonding to substrate 410,in one embodiment of the present invention. In this embodiment, glass420 is adapted to be bonded to substrate 410. It is appreciated thatblackening of the bonding side of glass 420 is performed analogously tothe blackening of glass 420 as described in FIG. 4B. It is furtherappreciated that the process of bonding glass 420 to substrate 410, suchas that result as shown in FIG. 4D, is analogous to the bondingdescribed in FIG. 4B.

FIG. 4D illustrates, in one example, the result of patterning, heattreating, and etching of glass 420, subsequent to bonding to substrate410 as described in FIG. 4B. FIG. 4D, in anther example, alsoillustrates glass 420, subsequent to patterning, heat treating, andetching performed thereon, having been bonded to substrate 410, inaccordance with bonding processes as described in FIG. 4B.

FIG. 4E illustrates another embodiment of the present invention, whereinsubstrate 410 has been treated such that substrate 410 is comprised oftwo portions of the same glass, e.g., D263 glass. In this embodiment,lower portion 410 is analogous to substrate FIG. 4A, and upper portion450 has had performed thereon a diffusing in of doping elements, so asto be made photochemically sensitive, and therefore responsive topatterning, heat treating, and etching.

FIG. 4F illustrates the result of patterning, heat treating, and etchingbeing performed upon upper portion 450, such that support structures areformed, and wherein FIG. 4F is, in dimension and function, analogous tothat which is shown in FIG. 4D, in one embodiment of the presentinvention.

In another method of fabricating a support structure, sandblasting isimplemented to fabricate the support structures. FIG. 4G shows substrate410, analogous to substrate 410 of FIG. 4A, has received a screenprinting of ceramic material 430 such that ceramic material 430 isdisposed on substrate 410. In one embodiment, ceramic material 430 iscomprised of a frit material which is fired at moderate temperatures,e.g., four hundred and fifty to six hundred degrees Celsius.

Subsequent to the disposition of ceramic material 430, via screenprinting, onto substrate 410, in one embodiment, a photoresist layer 440is deposited upon ceramic material 430, as shown in FIG. 4H. In oneembodiment, once photoresist layer 440 is deposited, it is exposed tothe pattern of the support structure. In one embodiment, oncephotoresist layer 440 has been exposed to the pattern of the supportstructure, photoresist layer 440 is then developed.

Still referring to FIG. 4H, subsequent to the developing of photoresistlayer 440, sandblasting by a sandblasting jet is applied thereto for theremoval of all areas of ceramic material 430 not covered by photoresist440, in one embodiment of the present invention.

FIG. 4J is a sequential illustration of FIG. 4H, subsequent tosandblasting applied to those areas of ceramic material 430 not coveredby photoresist layer 440, in one embodiment of the present invention.The resulting support structures, support structures 435 are shown inFIG. 4J.

In one embodiment of the present invention, ceramic material 430 iscomprised of two materials, a first material (a binder) which is softand easily etchable, and a second material (a filler) which is a hard orinert material. The etching process, initiated, then, in one embodiment,physically attacks, and in another embodiment, chemically attacks thesoft binder material such that the hard filler particles are loosenedand are subsequently easily physically removed, in one embodiment, andeasily chemically washed away, in another embodiment.

In one embodiment, if the chemical wash is a direction wash, e.g., aliquid jet, then those loosened hard filler materials exposed to theliquid jet will be carried away. It is appreciated that undercutting ofceramic material 430 is minimized, in part, by the fact that photoresistlayer 440 protects ceramic material 430 from the force of the liquidjet. This etch process is faster than previous methods because etchingand/or eroding the hard filler material is not required, as the hardfiller material is simply removed by the fluid of the liquid jet.

In another embodiment, an easily erodable material comprising a thickporous film can be used as a support structure disposed on substrate410. In the present embodiment, the pore membranes are attacked by theliquid jet. The etch is rapid due to the low density of the easilyerodable material. The directional nature of the liquid jet ensuresanistropy of the etch. It is appreciated that this etch process isselective because of the density difference in the support structurematerial and substrate 410 upon which it is disposed.

In another method of etching ceramic material 430, frozen submicronparticles of CO₂, produced as an aerosol, are utilized as an abrasiveetch, in one embodiment of the present invention. It is appreciated thatthe frozen CO₂ is not a hard as sand, and as such it will usually attacksofter materials, e.g., plastics, soft metals (Ag, Cu, Sn). When suchsoft materials are present in filler material of the support structuresbeing fabricated, these softer materials will be preferentially etched,in one embodiment. It is noted that the CO₂ spray will have enoughpressure to carry away loosened particles of the filler material. It isfurther noted that CO₂ particles are not hard enough to etch substrate410, such that an excellent etch stop is ensured. It is also noted thatthe CO₂ will sublime after heating, such that only residues from thefiller material loosened from substrate 410 will be present.

In yet another method of etching ceramic material 410, a chemical isused to attack the binder material but not otherwise attack the fillermaterial, in one embodiment of the present invention. In this method ofetching, the chemical is designed not to attack substrate 410. In oneembodiment, the etch is applied as a high pressure jet, such that fillerparticles, which are loosened, can be readily carried away.

It is appreciated that while the above method of etching is discussed inthe context of support structures fabricated out of glass, e.g., FIGS.4A-4J, the above described method of etching can easily be implementedin other support structure fabrication processes, such as thosedescribed in FIGS. 2A-2L, FIGS. 3A-3D, and FIGS. 5A-5D. It is furtherappreciated that the above method of etching can also be utilized inprocesses and fabrications not related to display device constructionwhere etching or sandblasting is necessary.

In one embodiment of the present invention, it is appreciated that thefabrication of a black matrix, e.g., black matrix 124 of FIG. 1, and thefabrication of an aluminum layer, e.g., aluminum layer 122 of FIG. 1, isperformed in conjunction with the fabrication of the support structuresas described in FIGS. 4A to 4J.

In another method to fabricate support structures, metal foil, in acontinuous or sheet form, is utilized in the fabrication process. FIG.5A is an illustration of substrate 510 upon which embodiments of thepresent invention may be practiced. Substrate 510 is analogous tosubstrate 210 of FIG. 2A. In one embodiment, substrate 510 is D263glass. In another embodiment, substrate 510 is an alternative glass.

FIG. 5B is an illustration of substrate 510 of FIG. 5A with anadditional layer of metal foil, metal foil 530, attached thereto. In oneembodiment, diffusion bonding is utilized to attach metal foil 530 tosubstrate 510. In another embodiment, thin film sealing glass isutilized to attach metal foil 530 to substrate 510. In anotherembodiment, anodic bonding is utilized to attach metal foil 530 tosubstrate 510. In one embodiment, metal foil 530 is a CTE (coefficientof thermal expansion) matched foil, e.g., Ni/Fe alloy, Ni/Fe/Co alloy,Nb, Mo, Titanium, Zirconium, and the like, and which has a thicknessranging from twenty five to fifty micrometers. It is appreciated that,in one embodiment, metal foil 530 is bonded to substrate 510 prior topatterning, heat treating, and etching being performed upon metal foil530. In one embodiment, CrO₃ is deposited upon the bonding side of metalfoil 530 prior to deposition and bonding upon substrate 530. CrO₃ is forthe blackening of the bonding side of metal foil 530.

FIG. 5C is an illustration of metal foil 530 patterned, heat treated,and etched prior to bonding to substrate 510, in one embodiment of thepresent invention. In this embodiment, metal foil 530 is adapted to bebonded to substrate 510. It is appreciated that blackening of thebonding side of metal foil 530 is performed analogously to theblackening of metal foil 530 as described in FIG. 5B. It is furtherappreciated that the process of bonding metal foil 530 to substrate 510,such as the result as shown in FIG. 5D, is analogous to the bondingdescribed in FIG. 5B.

FIG. 5D illustrates, in one example, the result of patterning, heattreating, and etching of metal foil 530, subsequent to bonding tosubstrate 510 as described in FIG. 5B. FIG. 5D, in anther example, alsoillustrates metal foil 530, subsequent to patterning, heat treating, andetching performed thereon, having been bonded to substrate 510, inaccordance with bonding processes as described in FIG. 5B.

In one embodiment of the present invention, it is appreciated that thefabrication of a black matrix, e.g., black matrix 124 of FIG. 1, and thefabrication of an aluminum layer, e.g., aluminum layer 122 of FIG. 1, isperformed in conjunction with the fabrication of the support structuresas described in FIGS. 5A to 5D.

It is appreciated that in the present invention, a method of fabricatinga support structure, the support structure being fabricated is describedas having a rectangular shape, in other embodiments, the supportstructure can be other shapes, e.g., cylindrical, cross like, and thelike. It is further appreciated that although the support structures areshown as a solid structure, in another embodiment, the supportstructures may be further comprised of voids or may be porous in nature.

The foregoing descriptions of specific embodiments of the presentinvention have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise forms disclosed, and obviously manymodifications and variations are possible in light of the aboveteaching. The embodiments were chosen and described in order to bestexplain the principles of the invention and its practical application,to thereby enable others skilled in the art to best utilize theinvention and various embodiments with various modifications as aresuited to the particular use contemplated. It is intended that the scopeof the invention be defined by the Claims appended hereto and theirequivalents.

What is claimed is:
 1. A method of fabricating a support structurecomprising; providing a mold for defining the physical dimension of saidsupport structure, said mold disposed upon a substrate surface;depositing a powder into said mold; compacting said powder in said mold,so as to form said support structure; and removing said mold from saidsubstrate surface upon which it is disposed, exposing said supportstructure, such that said support structure is implementable duringassembly of a display device.
 2. The method as recited in claim 1wherein said powder is a metal powder comprising heat expandingproperties compatible with said substrate surface upon which it isdisposed, and wherein said substrate surface is glass.
 3. The method asrecited in claim 1 wherein said powder is polished subsequent to thecompacting thereof and wherein said powder is getterable.
 4. The methodas recited in claim 1 wherein said compacting of said powder furthercomprises applying a vibratorial action to said powder, and wherein saidcompacting of said powder further comprises applying an increasedtemperature applied to said powder, such that a melting point of saidpowder is not attained by said increased temperature.
 5. The method asrecited in claim 1 wherein said removal of said mold further comprisesdissolution thereof, and wherein said removal of said mold furthercomprises applying a temperature elevated to a point of providingresidueless removal of said mold without adversely affecting said powderor said substrate surface upon which it is disposed.
 6. The method asrecited in claim 1 wherein said substrate surface is an anode faceplateand wherein said substrate is a cathode back plate, and wherein saidsupport structure is interposed between said anode faceplate and saidcathode back plate.
 7. The method as recited in claim 1 wherein saidmold is a photoresist mold.
 8. The method as recited in claim 1 whereinsaid display device is a field emission display.